Air and why we need it Lesson 17 of the world course of Mova's primary school: 18 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: the lesson at school .
0 Air is a mixture of gases: about four fifths is nitrogen, about one fifth is oxygen, and the rest is a little argon, a tiny amount of carbon dioxide and some water vapour. 1 People and animals breathe in air and use its oxygen to release energy from their food; they breathe out air with less oxygen and more carbon dioxide. 2 Green plants take in carbon dioxide and, using the energy of sunlight, make their food and give out oxygen. 3 Fire needs oxygen too: a flame goes out when its air is cut off, which is how a fire blanket smothers a fire. 4 The layer of air around the Earth, the atmosphere, also keeps us warm and protects us from harmful rays from the Sun. 5 For example, if you put a glass jar over a burning candle, the flame soon goes out, because it has used up much of the oxygen inside. 6 Air is a mixture of gases, mostly nitrogen and oxygen. 7 About one fifth of the air is oxygen. 8 Air holds only a tiny amount of carbon dioxide, much less than one part in a hundred. 9 We need oxygen to release energy from our food. 10 The air we breathe out has less oxygen and more carbon dioxide and water vapour than the air we breathe in, but it still has some oxygen. 11 Plants take in carbon dioxide and give out oxygen when they make food in sunlight. 12 Burning needs oxygen; without it a fire goes out, and a car engine, which burns fuel, needs air coming in for the same reason. 13 The air gets thinner the higher you go, so climbers on the highest mountains may carry oxygen. 14 Air takes up space: push an upturned glass straight down into water and the air trapped inside keeps the water out of most of the glass. 15 Air has weight: the air in a classroom weighs more than a hundred kilograms. 16 Most fish take in oxygen dissolved in the water through their gills. 17 Carbon dioxide in the air helps trap heat; more of it makes the Earth warmer. ← previous Climate zonesnext → Materials and their properties↑ back to World This page in Markdown → https://md.mova.elamur.ai/free/en/corpora/school/world/17-air-oxygen-carbon-dioxide/